With the wide application of electronic products such as notebook computers in people's work and life, portability has become a basic factor for people to evaluate an electronic product. As a result, electronic products such as ultra slim notebook computers have become the mainstream.
Currently, the cover member of many electronic products such as notebook computers is usually composed of a plastic casing and a metal base frame, wherein the metal base frame is fixed to the plastic casing to increase mechanical intensity of the plastic casing. In the prior art, the casing and the base frame are usually locked together by screws. However, to meet requirements of lighter, thinner, shorter and smaller electronic products, it is preferable to use a melting method to fix the casing with the base frame. The melting method includes: disposing a melt post on the plastic casing and a melt hole on the metal base frame; inserting the melt post into the melt hole to attach the casing to the base frame; and melting the melt post to fix the base frame to the casing.
As shown in FIGS. 1 and 2, a melt hole 21′ having a uniform diameter up and down is disposed on a base frame 2′. To relatively fix the melt post with the melt hole 21′, the melted portion of the melt post inserted into the melt hole 21′ should be spread around the outlet of the melt hole 21′. However, to ensure the fixing intensity between the melt post and the melt hole 21′, not only a lot of space around the melt hole 21′ will be occupied, the melt post also needs to protrude a certain height from the outlet surface of the melt hole 21′. Accordingly, the melted portion of the melt post is piled on the base frame 2′, thereby affecting the subsequent assembling process.
On the other hand, with a developing trend of ultra slim notebook computers, the alloy base frame is made as thin and as small as possible. As a result, the space around the melt hole becomes smaller. If the fixing intensity is increased by increasing the height of the melt post, the melted portion of the melt post will be piled on the base frame, thereby the subsequent assembly process is affected and the improved effect of the melt intensity is not so obvious.
Accordingly, there is a need to develop a fixing structure capable of providing a good fixing intensity between the casing and the base frame.